File this under "things that should be self-evident", but new research has come out showing that the reason people occasionally gouge their own eyes out isn't because they want to have sex with their mother, or due to Christian religious guilt — it's because of psychotic illness.

Alternately called oedipism, auto-enucleation, or self-enucleation, the act of removing one's eyes is a major (and thankfully uncommon) from of self-mutilation. However, historically, the act has been linked to the Freudian Oedipus Complex, or guilt about incestuous feelings towards the patient's mother. More recently, it's also been associated with Christian religious guilt, thanks to a verse from Matthew which says "and if thy right eye offend thee, pluck it out, and cast it from thee," which some patients who have mutilated themselves have referenced.

Thankfully, a new study has looked at this self-harm in a worldwide context, and have put paid to the notion that there's something religious or sexual about this. While self-enucleation is incredibly rare, it happens around the globe, and not just in Christian areas. Sexual or religious guilt was only associated with 25% of the cases, and none of them were Oedipal in nature.

What the authors believe is a far more likely cause of the mutilation is some form of psychosis, especially undiagnosed schizophrenia. There's a particular form of hallucination which can lead sufferers to believe that their eyeballs are possessed, or somehow posed a threat to their loved ones. It's these hallucinations and delusions which may drive them to such a monstrous form of self-harm, not sexual guilt about their feelings towards their mothers.